Sink-forming method



Jan. 14, 1969 HESS 3,421,466

V SINK-FORMING METHOD v Filed April 20, 1965 Shee t or 2 1e 19 15 I 2Lave/730k W a Hm Jan. 14, 1969 K. G. HESS V SINK-FORMING METHOD Sheet 2of 2 Filed April 20, 1965 United States Patent 01 14 Claims ABSTRACT OFTHE DISCLOSURE A method and apparatus for forming a unitary sink havinga plurality of bowls with bowl divider partitions therebetween from ablank of stainless steel in a doubleaction press. The press includes abase, a lower gripping member for the blank, a punch, and an uppermovable gripping member cooperating with the punch so that the uppergripping member descends prior to the punch to hold the blank betweenthe upper gripping member and the lower gripping member while the punchdescends to draw the blank. The base and lower gripping member haveopenings to form the female die for the press. A plurality of shims ofvarying thicknesses are placed between the base and the lower grippingmember to provide a variable gripping pressure between the upper andlower gripping members during the holding and the drawing stroke of thepress. Shims are located adjacent the bowl divider partitions of theblank so that the variable pressure is maximum adjacent the bowl dividerpartitions to permit minimum draw adjacent the partitions to eliminatewrinkling of the blank. Shims of a lesser thickness are also located atthe ends of the blank to compensate for any undesirable bowing of thedraw face yet to permit maximum draw at the ends of the blank.

Background the invention When attempting to press-form multi-bowl sinksfrom a single metal blank, the usual problem encountered is thatwrinkles are produced at the top of the multi-bowl sink adjacent thebowl divider of the final multi-bowl product. The problem has not beenovercome previously with the result that a plurality of single-bowls areformed and subsequently joined into a multi-bowl sink. This inventionavoids the necessity of subsequently joining individual bowls andefiiciently produces a multi-bowl sink from a single metal blank with noundesirable wrinkles. The present invention employs a double-actionpress to draw the blank into a desired shape in successive steps.Embodied in the method and structure is a means for applying a variablepressure about the periphery of the blank while it is being held anddrawn. By applying a maximum pressure at those points about theperiphery of the blank where wrinkling has occurred in previousattempts, a minimum draw is permitted at those points and the wrinklingis eliminated.

Summary of the invention This invention relates to an improved method offorming a multi-bowl sink.

More particularly, this invention relates to a method of forming amulti-bowl sink from a single blank of stainless steel by drawing theblank in a double-action press.

It is the primary object of this invention to provide an improved methodof forming a unitary multi-bowl sink, thus eliminating the necessity ofjoining a plurality of preformed single bowls to obtain the requiredmulti-bowl product.

It is a further object of this invention to provide a method ofpress-forming a multi-bowl sink from a single Patented Jan. 14, 1969"ice blank of stainless steel, yet a method which prevents the blankfrom wrinkling when the blank is deformed in a pressing operation.

Still another object of this invention is to provide a method andapparatus for forming a multi-bowl sink of the character described, themethod and apparatus embodying means for applying a variable pressureabout the periphery of the blank while it is being held and drawn, withthe pressure the maximum at those points about the periphery of theblank where wrinkling is prone to occur.

Other features and advantages of the invention will be apparent from hefollowing description taken in conjunction with the accompanyingdrawings.

Description of the drawing FIGURE 1 illustrates the principal parts of astandard double-action press embodying the form of punch of thisinvention; I

FIGURE 2 is a view taken generally along the line 2-2 of FIGURE 1;

FIGURE 3 is a sectional view taken generally along the line 3-3 ofFIGURE 2;

FIGURE 4 is a sectional view taken generally along the line 44 of FIGURE2;

FIGURE 5 is a bottom plan view of a deformed blank of stainless steel orthe like after the pressing and drawing operations of this invention andprior to trimming, to illustrate the areas of maximum and minimum draw;

FIGURE 6 shows a perspective view of the underside of the deformed blankof FIGURE 5 to illustrate the draw line on the bowls of the product ofthis invention prior to final trimming; and

FIGURE 7 shows the finished product of this invention.

Detailed description of the invention The following is a detaileddescription of the steps comprising my improved method of forming awrinklefree, multi-bowl sink from a single blank of stainless steel.

The method preferably embodies the use of a doubleaction toggle press,although the use of any suitable double-action press is anticipated.Referring to FIGURE 1, in a double-action press, two slides are employedto exert pressures on different portions of a metal blank, one to holdthe blank while the other draws it through dies to a desired shape. Asthe press descends, a blank holder and stripper 10 comprising the firstslide and a punch 11 comprising the second slide are so timed that theblank holder descends first and dwells to hold a metal blank 12 betweenthe blank holder 10 and a draw face 13 while the punch 11 subsequentlydescends to draw the blank. The draw face is mounted on a base 14, bothof which are provided with openings 15 which form the female die of thepress. A bolster plate 16 is provided to guide the punch during itsdownward stroke. The crux of this invention lies in the use of avariable gripping force on the metal blank which is held between theblank holder 10 and the draw face 13. If while the drawing is takingplace, a maximum pressure is applied at points about the periphery ofthe blank adjacent the areas where wrinkling of the blank will occur,minimum draw is effected at those points and the wrinkling iseliminated. The method by which the variable gripping pressure isapplied will be described later.

In my invention, the blank 12 of stainless steel or the like islubricated to control the slip when the blank is drawn in the press. Theblank is then placed on the draw face or die plate 13 which is securedto the base 14 of the press. The blank holder descends first to hold theblank with a variable pressure while the punch subsequently descends fora first draw which deforms the blank to partially form the bowls of thesink. The partially drawn blank is then removed and is subjected to anannealing process which softens the metal to facilitate more efficientdrawing during the second drawing operation. The blank is replaced onthe draw face for a second draw to completely form the bowls of thesink. The punch is designed to travel two distances on its two downwardstrokes so that it travels a shorter distance on its first drawingstroke to partially form the bowls of the sink and a longer stroke onits second or final draw to completely form the bowls of the sink. Asstated above, a variable gripping pressure between the blank holder andthe draw face is embodied in this invention to prevent wrinkling of theblank when deformed during the drawing operations.

In order to provide a variable gripping pressure on the blank, aplurality of stips of metal shims 18 and 19 are inserted atpredetermined locations between the draw face 13 and the base 14. Asseen in FIGURES 2 and 4, the shims are placed about the periphery of thefemale die openings 15 where the gripping pressure between the blankholder and the draw face is applied. The shims in elfect minutely deformor bow the draw face when under pressure and thus provide a variablepressure between the draw face and the blank holder. An example of howthe shims are arranged for processing a double-bowl sink has beenillustrated in the drawings and it should be understood that a largernumber of bowls could be so formed. For the present embodiment, theshims 18 are approximately of a 24 gauge thickness, or about .025 inch,and the shims 19 are approximately of a 20 gauge thickness, or about.037 inch. The shims 19 are approximately three times the length of theshims 18, both of which are generally the same width. As seen in FIGURES2 and 3, a 24 gauge shim 18 is positioned at each end of the female dieopening where the ends of the held blank would be located to provide fora minimum pressure and therefore a maximum draw at these points. A 20gauge shim 19 is positioned continuously along each side of the femaledie openings. In addition, a 24 gauge shim is placed on top of each ofthe 20 gauge shims adjacent each end of the bowl partition in order toprovide for a maximum pressure and therefore a minimum draw at thesecentral partition wrinkle-prone areas. In toto, the shims are of such athickness as to provide some gripping pressure at all points about theperiphery of the blank, but minimize the pressure at the far ends toallow maximum slipping and drawing at the ends and minimum Slipping anddrawing at the central partition wrinkle-prone areas.

FIGURES and 6 show the effect on a completely drawn blank of the abovedescribed positioning of the shims which produce the variable grippingforce between the blank holder and the draw face. It can be seen in FIG- URE 5 that maximum draw has been accomplished in the areas 20 and 21at each end of the once generally rectangular blank, and minimum drawhas been accomplished in the areas 22a and 22b adjacent the bowl dividerpartition 22. It is in these areas, 22a and 2217, where the undesirablewrinkling heretofore inherent in forming multibowl sinks from a singledrawing operation has resulted. FIGURE 6 shows a perspective of thedrawn blank as above described in FIGURE 4 and includes a broken lineshowing of the draw lines 23 on the bowls 24 of the sink effected by thevariable gripping pressure of this invention. Again, it can be seen thatthe maximum draw desired at the end of the metal blank (shown at 23a ofthe draw line) is accomplished by the shims of this invention and thatminimum draw resulting in no wrinkling is accomplished adjacent the bowldivider partition (shown at 23b of the draw line) of the final productof this invention.

FIGURE 6 shows a perspective view of the trimmed and final product ofthis invention comprising a unitary sink having bowls 24 with a bowldivider partition 22 therebetween and having an outwardly extendingflange 25 continuously about the upper periphery thereof for seating acounter top or the like.

This improved method of controlling the peripheral drawing of the blank,also results in a thicker bottom to the bowls 24 of the sink where thethickness is beneficial and results in less scrap to be removed from theperiphery of a given blank.

An improved and more eflicient method of producing an improvedmulti-bowl sink from a single sheet of stainless steel, by employing theuse of shims between the base of the press and the draw face to providea variable pressure. between the draw face and the blank holder of thepress has been provided. This variable pressure enables predeterminedcontrol of the slipping and drawing of the metal blank. The abovedescription as applied to a doublebowl sink is obviously adaptable toany desired number of bowls.

The foregoing detailed description has been given for clearance ofunderstanding only, and no unnecessary limtations should be understoodtherefrom, as some modifications may be obvious to those skilled in theart.

I claim:

1. The method of forming a multi-bowl sink from a blank of stainlesssteel which comprises the steps of applying a lurbicant to the blank;holding the blank with varying degrees of pressure about the peripheryof said blank to provide controlled slipping and drawing of said blank;and forming the bowls of the sink from the blank while said blank isheld with said varying pressure.

2. The method of forming a unitary sink having a plurality of bowls withbowl-divider partitions therebetween from a blank of stainless steelwhich comprises the steps of applying a lubricant to the blank; holdingthe blank with varying degrees of pressure with the pressure being at amaximum adjacent said bowl-divider partitions to have minimum draw ofsaid blank adjacent said partitions; and forming the bowls of the sinkfrom the blank while said blank is held with said varying pressure.

3. A unitary multi-bowl sink produced from a single blank of stainlesssteel, said sink comprising a plurality of bowls with outer upwardlyextending side walls, said side walls being provided with an outwardlyextending flange about the upper periphery thereof; a bowl dividingpartition between adjacent bowls, said partition being substantially thesame height as said outer side walls; said unitary multi-bowl sink beingproduced by the method described in claim 2.

4. The method of forming a multi-bowl sink from a blank of stainlesssteel which comprises the steps of applying a lubricant to the blank;holding the blank with varying degrees of pressure about the peripheryof said blank to provide controlled slipping and drawing of said blank;and deforming the blank by a plurality of pressing opera tions whilesaid blank is held with said varying pressure to form bowls of the sink.

5. A method of forming a unitary sink having a plurality of bowls withbowl-divider partitions therebetween from a blank of stainless steelcomprising the following steps: applying a lubricant to the blank;holding the blank with varying degrees of pressure around the peripheryof said blank, said pressure being at a miximum adjacent saidbowl-divider partitions to permit minimum draw of said blank adjacentsaid partitions; partially deforming the blank while held with saidvarying pressure to partially form the bowls of the sink; removing theblank and annealing said blank; again holding the blank with saidvarying pressure; and completely forming the bowls of the sink while theblank is held with said varying pressure.

6. A method of forming a unitary sink having a plurality of bowls withbowl-divider partitions therebetween from a blank of stainless steelcomprising the following steps: applying a lubricant to the blank;holding the blank with varying degrees of pressure around the peripheryof said blank, said pressure being at a miximum adjacent saidbowl-divider partitions to permit minimum draw of said blank adjacentsaid partitions; drawing the blank while held with said varying pressureto partially form the bowls of the sink; removing the blank andannealing said blank; again holding the blank with said varyingpressure; and further drawing the blank while held with said varyingpressure to completely form the bowls of the sink.

7. A unitary multi-bowl sink produced from a single blank of stainlesssteel by the method described in claim 6.

8. A means for providing controlled slipping and drawing in adouble-action press, comprising: a base for said press; a lower grippingmember in the form of a draw face secured to said base; an upper movablegripping member in the form of a blank holder; a punch cooperating withsaid upper gripping member so that said punch descends subsequent tosaid upper movable gripping member; openings through said base and saiddraw face to form a female die for said press; and a plurality of shimsof varying thicknesses placed at predetermined locations between saidbase and said draw face to provide a variable gripping pressure betweensaid draw face and said blank holder when said blank holder is movedinto pressure contact with said draw face during the holding and drawingstroke of said double-action press.

9. A means for forming a unitary sink having a plurality of bowls withbowl-divider partitions therebetween from a blank of stainless steel ina double-action press, comprising: a base for said press; a membersecured to said base in the form of a draw face to form a lower grippingmember of said blank; a punch for said press; an upper movable grippingmember for said blank in the form of a blank holder, said blank holdercooperating with said punch so that said blank holder descends prior tosaid punch to hold said blank between said blank holder and said drawface while said punch descends to draw the blank; openings through saidbase and said draw face to form a female die for said press; and aplurality of shims of varying thicknesses placed between said base andsaid draw face to provide a variable gripping pressure between said drawface and said blank holder during the holding and drawing stroke of saiddouble-action press, said shims being located adjacent the bowl-dividerpartition of said blank so that said variable pressure is a maximumadjacent said bowl-divider partitions to permit minimum draw adjacentsaid partitions to eliminate wrinkling of said blank.

10. A means for forming a unitary sink having a plurality of bowls withbowl-divider partitions therebetween from a blank of stainless steel ina double-action press or the like, comprising: a base for said press; alower gripping means for said blank in the form of a draw face securedto said base; a punch for said press; an upper movable gripping meansfor said blank in the form of a blank holder, said blank holdercooperating with said punch so that said blank holder descends prior tosaid punch to hold said blank between said bolster plate and said drawface while said punch descends to draw said blank; openings through saidbase and said draw face to form a female die for said press; and aplurality of shims of varying thicknesses placed between said base andsaid draw face about the periphery of said blank to provide a variablegripping pressure between said draw face and said blank holder duringthe holding and drawing stroke of said double-action press to providefor controlled slipping and drawing of said blank, said shims beinglocated adjacent the bowl-divider partitions of said blank so that saidvariable pressure is a maximum adjacent said bowldivider partitions topermit minimum draw adjacent said partitions to eliminate wrinkling ofsaid blank, said shims also being located at the ends of said blank tocompensate for any undesirable bowing of said draw face yet to permitmiximum draw at the ends of said blank.

11. A means for forming a unitary sink having a plurality of bowls withside walls, end walls, and bowldivider partitions from a blank ofstainless steel in a double-action press or the like, comprising: a basefor said press; a lower gripping means for said blank in the form of adraw face secured to said base; a punch for said press; an upper movablegripping means for said blank in the form of a blank holder, said blankholder cooperating with said punch so that said blank holder descendsprior to said punch to hold said blank between said blank holder andsaid draw face while said punch descends to draw said blank; openingsthrough said base and said draw face to form a female die for saidpress; A shim placed between said base and said draw face about theperiphery of said blank adjacent each of the end walls of said unitarysink; a second shim of a greater thickness then said first shim placedbetween said base and said draw face about the periphery of said blankcontinuously along the side of said unitary sink adjacent the side wallsthereof; and a shim placed between said base and said draw face on topof said second named shim adjacent the ends of each of said bowl-dividerpartitions.

12. A means for forming a unitary sink as in claim 11 wherein said firstshim and said third shim are of the same thickness.

13. A means for providing controlled slipping and drawing in adouble-action press, comprising: a base for said press; a first grippingmember in the form of a draw face secured to said base; a second movablegripping member in the form of a blank holder; a punch cooperating withsaid second gripping member so that said punch moves toward said baseand said first gripping member subsequent to said second movablegripping member mov ing toward said base; openings through said base andsaid draw face to form a female die for said press; and means to providea variable gripping pressure between said draw face and said blankholder at predetermined locations around said openings when said blankholder is moved into pressure contact with said draw face during theholding and drawing stroke of said double-action press.

14. A unitary multi-bowl sink produced from a single blank of stainlesssteel without any welding together of bowl sections, said sinkcomprising a plurality of bowls with outer upwardly extending sidewalls, said side walls being provided with an outwardly extending flangeabout the upper periphery thereof, a bowl dividing partition betweenadjacent bowls, said partition being substantially the same height assaid outer side walls, said unitary multi-bowl sink being formed from ablank while the blank is held with varying degrees of pressure with thepressure being at a miximum adjacent said bowl dividing partition.

References Cited UNITED STATES PATENTS 2,305,866 12/1942 Graf 113-1202,354,005 7/ 1944 Flowers 72-351 2,666,951 1/1954 Groove 72-3512,908,019 10/1959 Lyon 113-120 3,144,974 8/ 1964 Eichner et al. 113-120FOREIGN PATENTS 566,123 11/1958 Canada.

CHARLES W. LANHAM, Primary Examiner.

RONALD D. GREFE, Assistant Examiner.

US. Cl. X.R. 72-351

